HIV is one of the deadliest viruses on the planet,
newly infecting about 1.7 million people in 2018
Since the early days of the epidemic,
the virus itself has confounded researchers
who have long been searching for vaccine to prevent its spread
and after years of slow progress
that search may soon be over
The epidemic as we now know
it is thought to have started in the mid to late 1970s
but it wasn’t until 1983
that the HIV virus was first identified and isolated.
By that point, HIV had begun to rapidly spread around the world
—and since the epidemic began,
it’s claimed the lives of over 32 million people.
To understand why this virus causes so much harm,
we first need to know how it invades the body.
First off, it’s a retrovirus,
which is a type of virus
that inserts a copy of its genome into the DNA of a host cell—
in HIV’s case,
T-helper cells which help our immune system fight off infection.
After latching onto the cell, HIV fuses with it,
integrating its genetic information with the new host’s DNA.
The infected cell then produces
more HIV proteins
which are eventually released into the bloodstream where they continue to replicate
If left untreated,
HIV severely weakens the immune system’s ability to function properly
—this final stage of the infection is AIDS.
And it’s precisely the virus’ unique characteristics
which allow it to propagate inside the human body
that also make it so difficult to tackle
HIV is a remarkably small virus.
It has few genes comprised in it,
regardless of how small and simple it may be
it has very complex dynamic interactions
with the human immune system.
There’s currently a few ways to stop HIV
from progressing in its life cycle.
Specific drugs have been developed
that can stop the virus from attaching to T-helper cells,
while other types of drugs work to prevent the virus
from taking control of the cell’s nucleus and enter the bloodstream.
Called antiretroviral therapy,
this drug combination works well
but is expensive and requires lifelong upkeep.
In those resource constrained areas
or where the stigma of HIV is still a major problem,
prevention methods that require daily pills
may still limit the number of individuals who would have access to these.
It’s only through the application of very highly effective vaccaines
that we’ve been able to control an infection
that spread around the globe, and eventually eradicate that.
But that doesn’t mean developing a vaccine is easy
There aren’t many good models to reference for research in humans,
which means we don’t know what the body’s immune response looks like
when trying to protect itself.
HIV’s extraordinary diversity and ability to rapidly mutate
are also huge obstacles in getting a grip on the virus.
Just recently, researchers announced that they’d IDed a new strain,
the first in 19 years.
Despite this, there has been huge progress made in the last decade.
In 2009, researchers declared that a vaccine
trial done in Thailand had protected a significant minority of humans
against the disease for the first time ever.
RV144 is a combination of two genetically engineered vaccines,
neither of which had worked before in humans.
We observed a modest level of efficacy over three and a half years—about 30%.
我们经过三年半的观察 发现这种疫苗的功效大约有30% 不算太好
So, we have initiated a clinical trial in South Africa
that is marching along the path to try to confirm these findings from the Thai trial
and extend those findings through a number of approaches.
As the world’s largest publicly-funded international collaboration focused on
the development of vaccines to prevent HIV and AIDS,
HVTN has conducted all phases of clinical trials
that have involved thousands of people.
In addition to two massive trials to test whether giving
antibodies to patients can protect them from HIV infection,
as of this year the group has also fully enrolled two similarly ambitious vaccine trials
called HVTN 702 and 705.
These regimen were designed to test whether patients
given a vaccine can create antibodies on their own
Both vary slightly in their approach—
702 is based off of the Thai trial,
while 705 is focusing on overcoming the viruses’ genetic diversity.
What’s very exciting is that
the immune responses elicited by these three different
vaccine strategies is different within each clinical trial,
but there’s similarities across them
And we’re looking for specific immune responses
that we will correlate with vaccine efficacy with just a few dozen people
that will eventually lead us to
a more globally effective vaccine
that could be used across different populations and routes of exposure.
With hopes high, and even higher stakes,
the mood of the vaccine research seems to be one of cautious optimism.
But results of both the 705 and 702 vaccine regimens
won’t be in until late 2021 and 2022,
when the trials are expected to close.
They will certainly be a success and
that we’ll get a clear answer as to
whether or not these vaccines worked
but I think we also have to be measured in our expectations
And that this is one of the most formidable biomedical challenges
we’ve ever undertaken as a society, as a global research community.
If you want to learn more about the search for a potential HIV cure,
check out this episode of How Close Are We.
请看How Close Are We 的这期节目
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HIV is one of the deadliest viruses on the planet,